corona 4 caustics

[super gnu]

so, the new caustics system in Corona looks very impressive. is it likely to sneak over to vray too, given the "bidirectional developement" which was suggested when chaos purchased it? caustics and bump mapping have always been the two major weak spots for me in vray. to be honest im still somewhat confused re. Caustics vs GI caustics.. i recently did a can with condensation on, and, after getting a nice hint here, and ditching my struggles with photon mapping, got some reasonable caustics through the droplets using just the gi caustics in vray GPU...

is this method somehow missing part of the total caustic solution or inferior in some way to the photon mapped or corona methods? I did notice a fairly major slowdown in the areas with reflected caustics using that method.. it basically doubled the rendertime.

[matanov]

A new caustics system is planned and it will surface in some of the future releases.

Bump in V-Ray was rewritten in Update 2. Do you have some example of being a "weak spot" after that?

[super gnu]

i dont have a specific example to hand, but ive always found it a bit... weak? not convincing? i didnt notice a change since updated 2, but then i wasnt specifically looking for it.

issues ive had are:

recreating a layered c4d/corona corroded bronze material in max/vray, using the same maps.. same geometry, and same lights. the corona render i was matching to had lovely subtle, sharp, crunchy corrosion that looked totally 3d and very nice. whatever i did in max/vray, (multipliers, filtering, gamma, gpu/cpu) it never looked half as convincing.. either nonexistant, or, if multipliers jacked up to the sky, more visible, but then weird and fake in other places.

vray gpu bump being something like 30x stronger than cpu vray bump. - i appreciate they will never perfectly match, but it must be possible to get closer than this? at least so we can render purchased vray assets on gpu without them looking super odd.

strong bump multipliers causing weird effects on curved objects (odd lighting/facetting) -maybe this is something that affects all renderers.. im not sure.

no bump deformation on shadows. - this is apparently half working in vray, but the option is not exposed in the interface, due to it not working well enough.

[vlado]

It would be interesting to post some specific examples of the V-Ray vs Corona differences.

As for the CPU vs GPU, if you use VRayColor2Bump on the CPU, then the results will generally match between the two. Either that, or using normal maps. In general, I haven't found any two render engines that produce the same results with bump mapping; normal maps tend to be more consistent.

With that said, it might be possible to get the results to match closer.

Best regards,
Vlado

[super gnu]

well the only comparison i have between Corona and Vray is the aforementioned bronze. problematically its a pretty complex multilayer shader which i copied by hand from the corona/c4d version. there are some variances due to the vraydirt working differently from the corona one, and other subtle differences due to colour correct nodes being different. ive eyeballed it to match as close as possible, but its missing the crusty effect. i put it down to bump being the issue, but i could not say for sure that it isnt some masking issue between the layers. its harder to see the greeny blistery bits on mine, but if you look carefully, they are there, just much less evident as they appear flat. job is done and dusted now.

[fixeighted]

I remember one Grant Warwick vid where specifically he mentioned the incomparable difference between Corona's bump versus Vray's, with Corona being so noticeably better and more realistic.
This is now an old video but obviously the same is still true. It's almost like Corona uses more iterations of, say, black to white, than Vray does, so appearing that Vray's clipped somehow, if that makes sense.